In Keller U.S. Pat. No. 3,986,623, issued Oct. 19, 1976, and Keller U.S. Pat. No. 3,777,908, issued Dec., 1973, apparatus is disclosed for plucking increments of fiber from a plurality of bales arranged behind a plurality of hopper feeders, and delivering such fiber increments to the hopper feeders in a controlled, predetermined cycle. The apparatus includes a pick-up head arranged on an elevated trackway located over the plurality of hopper feeders and the bales adjacent thereto, and the control system for the pick-up head constantly monitors the plurality of hopper feeders to determine when one or more of them is generating a signal indicating that additional fiber is required by the signaling hopper feeder. When such a signal is generated by one of the hopper feeders, the pick-up head is caused to move to the signaling hopper feeder, then the pick-up head moves, in sequence, to pluck an increment of fiber from selected bales adjacent the signaling hopper feeder and to deliver each such fiber increment to a position above the hopper feeder where the fiber increment is released so that it falls into the hopper feeder.
One of the significant advantages of the aforementioned apparatus, as compared with manual feeding of fiber to the hopper feeder, is the fact that a worker need not be constantly exposed to the fiber dust that is generated when layers or fiber are separated from the bales and dumped into the hopper feeders. Nevertheless, this fiber dust still presents a less severe problem because workmen are present in the general vicinity of the aforementioned apparatus during certain times, as for exmple, when exhausted bales are replaced with new bales.
While most mills which utilize apparatus of the aforesaid type have large existing vacuum systems designed to constantly recirculate and filter air within the mill, the fiber dust nevertheless is present in the environment for a predetermined length of time before it reaches the intak of such existing vacuum systems, and small particles of fiber dust are often quite difficult to collect once they are generally propagated into the environment.
In an effort to avoid drawbacks of utilizing the existing vacuum or air cleaning systems of the mill, it has been proposed that an individual, separate vacuum system be installed at each feeder hopper for constant operation whereby fiber dust generated by the increments of fiber falling into a hopper feeder is sucked into the individual vacuum system therefor and removed before being universally propagated into the surrounding environment. Separate or individual vacuum systems of this sort would serve to reduce the amount of fiber dust in the air, but they have the disadvantage of beng expensive. If each hopper feeder is provided with its own vacuum stystem, the initial costs and the operating costs therefor are increased, and this expense can become particularly significant in installations using a large number of hopper feeders. Additionally, even if suction ducts are connected to the existing mill vacuum system and led to each hopper feeder for the usual continuous suction operation, such additional ducts would impose a significant extra load on the existing vacuum system, perhaps to the point of requiring larger suction equipment in installations having a large number of hopper feeders. Finally, such individual suction systems, or add-on ducts, would be very inefficient from an energy consumption and suction equipment utilization standpoint because, in the usual multi-hopper feeder installations, the suction systems for all of the hopper feeders would be operating constantly even though, as pointed out above, the pick-up head only delivers fiber increments to one hopper feeder at a time.
By virtue of present invention, each hopper feeder is provided with an individual suction conduit that can be connected directly to the existing mill vacuum system without imposing an undue load thereon because each suction conduit is controlled in conjunction with the operation of the pick-up head so as to create a vacuum only when the pick-up head is actually delivering fiber increments to the hopper feeder associated with such suction conduit.